283 lines
8.5 KiB
Go
283 lines
8.5 KiB
Go
package route
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import (
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"context"
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"errors"
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"net/netip"
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"strings"
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"time"
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"github.com/sagernet/sing-box/adapter"
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C "github.com/sagernet/sing-box/constant"
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"github.com/sagernet/sing-dns"
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"github.com/sagernet/sing/common/cache"
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E "github.com/sagernet/sing/common/exceptions"
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F "github.com/sagernet/sing/common/format"
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M "github.com/sagernet/sing/common/metadata"
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mDNS "github.com/miekg/dns"
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)
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type DNSReverseMapping struct {
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cache *cache.LruCache[netip.Addr, string]
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}
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func NewDNSReverseMapping() *DNSReverseMapping {
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return &DNSReverseMapping{
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cache: cache.New[netip.Addr, string](),
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}
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}
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func (m *DNSReverseMapping) Save(address netip.Addr, domain string, ttl int) {
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m.cache.StoreWithExpire(address, domain, time.Now().Add(time.Duration(ttl)*time.Second))
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}
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func (m *DNSReverseMapping) Query(address netip.Addr) (string, bool) {
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domain, loaded := m.cache.Load(address)
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return domain, loaded
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}
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func (r *Router) matchDNS(ctx context.Context, allowFakeIP bool, index int) (context.Context, dns.Transport, dns.DomainStrategy, adapter.DNSRule, int) {
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metadata := adapter.ContextFrom(ctx)
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if metadata == nil {
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panic("no context")
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}
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if index < len(r.dnsRules) {
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dnsRules := r.dnsRules
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if index != -1 {
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dnsRules = dnsRules[index+1:]
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}
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for currentRuleIndex, rule := range dnsRules {
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metadata.ResetRuleCache()
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if rule.Match(metadata) {
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detour := rule.Outbound()
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transport, loaded := r.transportMap[detour]
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if !loaded {
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r.dnsLogger.ErrorContext(ctx, "transport not found: ", detour)
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continue
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}
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_, isFakeIP := transport.(adapter.FakeIPTransport)
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if isFakeIP && !allowFakeIP {
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continue
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}
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ruleIndex := currentRuleIndex
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if index != -1 {
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ruleIndex += index + 1
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}
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r.dnsLogger.DebugContext(ctx, "match[", ruleIndex, "] ", rule.String(), " => ", detour)
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if isFakeIP || rule.DisableCache() {
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ctx = dns.ContextWithDisableCache(ctx, true)
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}
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if rewriteTTL := rule.RewriteTTL(); rewriteTTL != nil {
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ctx = dns.ContextWithRewriteTTL(ctx, *rewriteTTL)
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}
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if clientSubnet := rule.ClientSubnet(); clientSubnet != nil {
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ctx = dns.ContextWithClientSubnet(ctx, *clientSubnet)
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}
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if domainStrategy, dsLoaded := r.transportDomainStrategy[transport]; dsLoaded {
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return ctx, transport, domainStrategy, rule, ruleIndex
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} else {
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return ctx, transport, r.defaultDomainStrategy, rule, ruleIndex
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}
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}
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}
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}
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if domainStrategy, dsLoaded := r.transportDomainStrategy[r.defaultTransport]; dsLoaded {
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return ctx, r.defaultTransport, domainStrategy, nil, -1
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} else {
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return ctx, r.defaultTransport, r.defaultDomainStrategy, nil, -1
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}
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}
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func (r *Router) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) {
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if len(message.Question) > 0 {
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r.dnsLogger.DebugContext(ctx, "exchange ", formatQuestion(message.Question[0].String()))
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}
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var (
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response *mDNS.Msg
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cached bool
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transport dns.Transport
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err error
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)
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response, cached = r.dnsClient.ExchangeCache(ctx, message)
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if !cached {
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var metadata *adapter.InboundContext
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ctx, metadata = adapter.AppendContext(ctx)
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if len(message.Question) > 0 {
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metadata.QueryType = message.Question[0].Qtype
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switch metadata.QueryType {
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case mDNS.TypeA:
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metadata.IPVersion = 4
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case mDNS.TypeAAAA:
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metadata.IPVersion = 6
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}
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metadata.Domain = fqdnToDomain(message.Question[0].Name)
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}
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var (
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strategy dns.DomainStrategy
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rule adapter.DNSRule
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ruleIndex int
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)
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ruleIndex = -1
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for {
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var (
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dnsCtx context.Context
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cancel context.CancelFunc
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addressLimit bool
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)
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dnsCtx, transport, strategy, rule, ruleIndex = r.matchDNS(ctx, true, ruleIndex)
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dnsCtx, cancel = context.WithTimeout(dnsCtx, C.DNSTimeout)
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if rule != nil && rule.WithAddressLimit() && isAddressQuery(message) {
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addressLimit = true
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response, err = r.dnsClient.ExchangeWithResponseCheck(dnsCtx, transport, message, strategy, func(response *mDNS.Msg) bool {
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metadata.DestinationAddresses, _ = dns.MessageToAddresses(response)
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return rule.MatchAddressLimit(metadata)
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})
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} else {
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addressLimit = false
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response, err = r.dnsClient.Exchange(dnsCtx, transport, message, strategy)
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}
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cancel()
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var rejected bool
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if err != nil {
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if errors.Is(err, dns.ErrResponseRejectedCached) {
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rejected = true
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r.dnsLogger.DebugContext(ctx, E.Cause(err, "response rejected for ", formatQuestion(message.Question[0].String())), " (cached)")
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} else if errors.Is(err, dns.ErrResponseRejected) {
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rejected = true
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r.dnsLogger.DebugContext(ctx, E.Cause(err, "response rejected for ", formatQuestion(message.Question[0].String())))
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} else if len(message.Question) > 0 {
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r.dnsLogger.ErrorContext(ctx, E.Cause(err, "exchange failed for ", formatQuestion(message.Question[0].String())))
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} else {
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r.dnsLogger.ErrorContext(ctx, E.Cause(err, "exchange failed for <empty query>"))
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}
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}
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if addressLimit && rejected {
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continue
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}
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break
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}
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}
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if err != nil {
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return nil, err
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}
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if r.dnsReverseMapping != nil && len(message.Question) > 0 && response != nil && len(response.Answer) > 0 {
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if _, isFakeIP := transport.(adapter.FakeIPTransport); !isFakeIP {
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for _, answer := range response.Answer {
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switch record := answer.(type) {
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case *mDNS.A:
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r.dnsReverseMapping.Save(M.AddrFromIP(record.A), fqdnToDomain(record.Hdr.Name), int(record.Hdr.Ttl))
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case *mDNS.AAAA:
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r.dnsReverseMapping.Save(M.AddrFromIP(record.AAAA), fqdnToDomain(record.Hdr.Name), int(record.Hdr.Ttl))
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}
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}
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}
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}
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return response, nil
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}
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func (r *Router) Lookup(ctx context.Context, domain string, strategy dns.DomainStrategy) ([]netip.Addr, error) {
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var (
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responseAddrs []netip.Addr
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cached bool
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err error
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)
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responseAddrs, cached = r.dnsClient.LookupCache(ctx, domain, strategy)
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if cached {
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return responseAddrs, nil
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}
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r.dnsLogger.DebugContext(ctx, "lookup domain ", domain)
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ctx, metadata := adapter.AppendContext(ctx)
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metadata.Domain = domain
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var (
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transport dns.Transport
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transportStrategy dns.DomainStrategy
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rule adapter.DNSRule
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ruleIndex int
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)
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ruleIndex = -1
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for {
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var (
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dnsCtx context.Context
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cancel context.CancelFunc
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addressLimit bool
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)
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metadata.ResetRuleCache()
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metadata.DestinationAddresses = nil
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dnsCtx, transport, transportStrategy, rule, ruleIndex = r.matchDNS(ctx, false, ruleIndex)
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if strategy == dns.DomainStrategyAsIS {
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strategy = transportStrategy
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}
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dnsCtx, cancel = context.WithTimeout(dnsCtx, C.DNSTimeout)
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if rule != nil && rule.WithAddressLimit() {
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addressLimit = true
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responseAddrs, err = r.dnsClient.LookupWithResponseCheck(dnsCtx, transport, domain, strategy, func(responseAddrs []netip.Addr) bool {
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metadata.DestinationAddresses = responseAddrs
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return rule.MatchAddressLimit(metadata)
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})
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} else {
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addressLimit = false
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responseAddrs, err = r.dnsClient.Lookup(dnsCtx, transport, domain, strategy)
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}
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cancel()
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if err != nil {
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if errors.Is(err, dns.ErrResponseRejectedCached) {
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r.dnsLogger.DebugContext(ctx, "response rejected for ", domain, " (cached)")
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} else if errors.Is(err, dns.ErrResponseRejected) {
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r.dnsLogger.DebugContext(ctx, "response rejected for ", domain)
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} else {
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r.dnsLogger.ErrorContext(ctx, E.Cause(err, "lookup failed for ", domain))
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}
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} else if len(responseAddrs) == 0 {
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r.dnsLogger.ErrorContext(ctx, "lookup failed for ", domain, ": empty result")
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err = dns.RCodeNameError
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}
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if !addressLimit || err == nil {
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break
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}
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}
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if len(responseAddrs) > 0 {
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r.dnsLogger.InfoContext(ctx, "lookup succeed for ", domain, ": ", strings.Join(F.MapToString(responseAddrs), " "))
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}
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return responseAddrs, err
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}
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func (r *Router) LookupDefault(ctx context.Context, domain string) ([]netip.Addr, error) {
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return r.Lookup(ctx, domain, dns.DomainStrategyAsIS)
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}
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func (r *Router) ClearDNSCache() {
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r.dnsClient.ClearCache()
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if r.platformInterface != nil {
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r.platformInterface.ClearDNSCache()
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}
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}
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func isAddressQuery(message *mDNS.Msg) bool {
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for _, question := range message.Question {
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if question.Qtype == mDNS.TypeA || question.Qtype == mDNS.TypeAAAA {
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return true
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}
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}
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return false
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}
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func fqdnToDomain(fqdn string) string {
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if mDNS.IsFqdn(fqdn) {
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return fqdn[:len(fqdn)-1]
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}
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return fqdn
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}
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func formatQuestion(string string) string {
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if strings.HasPrefix(string, ";") {
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string = string[1:]
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}
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string = strings.ReplaceAll(string, "\t", " ")
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for strings.Contains(string, " ") {
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string = strings.ReplaceAll(string, " ", " ")
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}
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return string
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}
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